Gameplay for Sonic Battle: Amped Up! is very much like its predecessor, but greatly upgraded. Players can explore the overworld as in the original, but the overworld is now in 3D and fully explorable, similar to the Adventure Fields of Sonic Adventure. Characters are capable of using their dash and air actions to traverse the overworld, allowing players to further explore locations, which can reward the player with upgrades, new arenas, and easter eggs. In the case of multiple characters in a "party", the player is allowed to switch between characters to use their individual movement abilities. Glowing green rings on the ground (similar to the ones used to indicate upgrades in SA and SA2) indicate optional battles, allowing for either fighting optional enemies or training with characters. Red glowing rings however, indicate mandatory battles required to continue the plot. The player can't pass the red ring's location until they complete the battle, and access to other locations involved in the story are likewise blocked by red barriers; players can't access the location until all required battles are completed, which is indicated by the number of barriers. The opponent(s) the player is supposed to fight stand in the center of the green and red rings. Small glowing yellow rings however allow the player to talk to characters to gather hints and information.
Fighting in Amped Up! is vastly upgraded compared to its predecessor. Players now have two different ways to play the game in-battle. The first is based on the playstyle of the original Sonic Battle, taking place in arenas from a top-view, but uses 3D graphics like those of Sonic Chronicles. Attacks are still aimed by directing the character to aim in the desired location. The other option is drastically different however. The fighting takes place fully 3D versions of arenas. Long-range attacks are now aimed by targeting the opponent prior to using the attack. Special techniques are still categorized as the following:
- Shot: mid-to-long range attacks.
- Power: signature attacks that can vary between characters, but are often close-range attacks.
- Trap: attacks where the character places, launches, or releases explosives.
Prior to the beginning of battle and prior to respawning, the player is capable of designating Shot, Power, and Trap techniques to the following uses:
- Ground: The special technique used in its basic form while the character is on the ground.
- Aerial: A variant of the special technique designated to aerial use, which are typically used as an air-to-ground attack while the character is up in the air.
- Guard: An attack unusable in battle. When a special technique is set to this designation, the character is automatically protected from attacks of the same category. For example, designating "Power" to "Guard" automatically protects the character from all "Power" techniques.
Once again, all characters are capable of healing themselves at rates that vary between each character. Blocking special techniques and healing fills up the character's "Amp Guage". Completely filling the Amp Guage causes the character to glow, and causes their next special technique to be an automatic 1-hit K.O. However, the techniques can still be blocked, and blocking it completely fills the Amp Gauge.
However, the biggest change to gameplay are "upgrades". Players are capable of getting generic upgrades by buying them from stores, which enhance speed, power of basic attacks, defense, HP, and more. However, all characters have three unique upgrades that can only be found by exploring the overworld. Each upgrade enhances the power of either the "Shot", "Power", or "Trap" technique of the character. These upgraded versions of an attack can be used by sacrificing a portion of energy from the character's Amp Guage.
Battles are again designated as either "Point", "Survival" or "Time". Point requires players to be the first to reach a designated number of points first, which is done by K.O.ing opponents to get points. Survival requires the player to be the last one standing, which is done by K.O.ing the opponents until they run out of lives. Time battles require the player to meet a certain objective before or until the timer runs out. New options include "Capture", where the player must be the first to take seven Chaos Emeralds to a designated point, "Point Timer", where the victor is decided by who can get the most points in a designated time limit, and "Live or Die", where the player must continuously fight off enemies without dying until time runs out.
After months of inactivity, a sudden and bizarre reaction causes Emerl's Gizoid programming to reawaken! Seemingly by coincidence, G.U.N. also unveils their latest creation: Mel the Hedgehog, a hedgehog with bizarrely similar copying abilities. Now, the heroes must discover the hidden secrets that connect Emerl and Mel, while protecting the two from villainous foes.
- Sonic the Hedgehog
- Miles "Tails" Power
- Knuckles the Echidna
- Amy Rose
- Shadow the Hedgehog
- Rouge the Bat
- E-123 Omega
- Cream the Rabbit and Cheese
- Big the Cat
- Tikal the Echidna
- Metal Sonic
- Metal Knuckles
- Bean the Dynamite
- Bark the Polar Bear
- Nack the Weasel